Power distribution systems, or bus bars, are conductive plates including a plurality of holes for receiving electrical components such as insulated gate bi-polar transistor (IGBT) modules or circuit breakers, for example. The conductive plates may be made of any, and/or plated by, conductive material such as copper, aluminum, brass, or nickel, for example. The electrical components have various connection apparatus, including bushings, disposed proximate the bus bar holes. Generally, the bushings are soldered or welded to the bus bar and therefore suffer from common problems including compromised planarity, particularly in multilayer bus bars, reduced electrical connectivity and weak physical connection due to the introduction of the solder, corrosion, and thermal distortion. Such prior art bus bars also require substantial labor time and material expense to manufacture due to the soldering of each bushing, and associated flattening of the solder to provide a planar surface, and due to a preference for using relatively expensive copper bushings with copper bus bars due to the difficulty adhering different conductive materials, such as aluminum. Significantly, soldered bushing are not removable in the field and a failure may require replacement of the whole bus bar assembly.
Many of the above issues have been mitigated in the art such as by U.S. Pat. Nos. 7,7758,19 and 7,425,144 entitled “Buss Plate Bushing Retainer and Assembly Thereof” which disclose a cylindrical retainer for holding two bushing portions in place proximate a hole of a bus bar. While such connection apparatus do not require soldering and still provide reliable electrical connectivity, they are only removable using a tool to engage a detent in the retainer thereby requiring additional time for replacement in the field as well as increased likelihood of deformation of the retainer or other portion of the connection apparatus.
Accordingly, there is a need for a bus bar connection apparatus that does not require soldering, provides reliable electrical connectivity even with disparate conductive materials, and is easily released and replaced in the field.
Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate several embodiments of the invention but should not be construed as limiting the scope of the invention in any manner.